DNDC stands for D e n itrification and D e c omposition, two - - PDF document

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DNDC and Its Applications

Changsheng Li

Institute for the Study of Earth, Oceans and Space University of New Hampshire

DNDC stands for Denitrification and Decomposition, two processes dominating loss of N and C from soil into the atmosphere, respectively.

Transformation & transport

• f chemical

elements

Mechanical movement Dissolution / crystallization Combination / decomposition Oxidation / reduction Adsorption / desorption Complexation / decomplexation Assimilation / dissimilation Gravity Radiation Temperature Moisture Eh pH Substrates Climate Soil properties Vegetation Anthropogenic activities

Biochemical & geochemical reactions Environmental factors Ecological drivers

Biogeochemical Model is a Mathematical Expression of Biogeochemical Field

The DNDC model is a result of more than 10-year international efforts with researchers from the U.S., China, Germany, the U.K., Canada, Australia, New Zealand, the Netherlands, and Japan.

The DNDC Model

ecological drivers Climate Soil Vegetation Human activity soil environmental factors Temperature Moisture pH Substrates: NH4

+, NO3

• , DOC

Eh

Denitrification Nitrification Fermentation Decomposition Plant growth Soil climate

NH4

+

clay- NH4

+

NH3 DOC nitrifiers NO3

• N2O

NO NH3 DOC NO3

• NO

N2O N2 NO2

• nitrate

denitrifier nitrite denitrifier N2O denitrifier CH4 CH4 production CH4 oxidation CH4 transport soil Eh aerenchyma DOC soil temp profile soil moist profile soil Eh profile O2 diffusion O2 use vertical water flow very labile labile resistant litter labile resistant labile resistant microbes humads passive humus CO2 DOC NH4

+

roots stems grain N-demand N-uptake water demand water uptake water stress daily growth root respiration potential evapotrans. LAI-regulated albedo evap. trans. effect of temperature and moisture on decomposition annual average temp.

Input Parameters

• 1. Climate:
• Daily air temperature and precipitation;
• Solar radiation;
• Atmospheric N deposition;
• 2. Soil:
• Bulk density;
• Texture (clay fraction);
• Total organic C content;
• pH;
• 3. Management:- Crop type and rotation;
• Tillage;
• Irrigation;
• Fertilization;
• Manure amendment;
• Grazing.

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Output

• 1. Crop: - Photosynthesis;
• Respiration;
• Water and N demands/uptake;
• Biomass allocation;
• Yield and litter production;
• 2. Soil: - Temperature, moisture, pH and Eh profiles;
• SOC dynamics;
• N leaching;
• Emissions of N2O, NO, N2, NH3, CH4 and CO2

Climate

• Temperature
• Precipitation
• N deposition

Soil properties

• Texture
• Organic matter
• Bulk density
• pH

Management

• Crop rotation
• Tillage
• Fertilization
• Manure use
• Irrigation
• Grazing

Model tracking fundamental biochemical & geochemical processes Dynamics

• f soil water,

NH4, NO3, and DOC Used by soil microbes Used by plants Emissions of N2O, NO, N2, CH4 and CO2 Growth of crop biomass Competition

Biogeochemical Model Predicts Impacts of Alternative Management

• n Crop Yield and Environmental Safety

INPUT INPUT INPUT OUTPUT PROCESSES

N leaching

Model Validation

30 60 90 120 150 180 210 240 270 300 330 360 10 20 30 40 Julian day CO2 emission rate, kg C/ha/day Measured CO2 Simulated total CO2 Simulated root respiration Tillage Winter wheat field

Comparison on CO2 emissions from a silty loam soil in a tilled and fertilized witer wheat field in Columbia, Missouri

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Lianshui, Jiangsu, China, 1983-1992

0.002 0.004 0.006 0.008 1 2 3 4 5 6 7 8 9 1 0 Year

Yucheng, Shandong, China, 1986-94

0.002 0.004 0.006 0.008 1 2 3 4 5 6 7 8 9 1 0 Year Yueyang, Hunan, China, 1986-90 0.01 0.02 0.03 1 2 3 4 5 6 Year

Pingliang, Gansu, China, 1979-86

0.002 0.004 0.006 0.008 1 2 3 4 5 6 7 8

Year

DNDC captured long-term SOC dynamics observed at four crop fields in China

• Lianshui, Jiangsu
• Yucheng, Shandong
• Pingliang, Gansu
• Yueyiang, Hunan

N2O + N2 Fluxes from a Grassland at Berkshire, England, May 28-June 28, 1981 100 200 300 400 500 600 700 1 4 7 1 4 9 1 5 1 1 5 3 1 5 5 1 5 7 1 5 9 1 6 1 1 6 3 1 6 5 1 6 7 1 6 9 1 7 1 1 7 3 1 7 5 1 7 7 Day N 2 O + N 2 fl u x , g N /h a /d a y Field Model

Dynamics of Several Soil Environmental Factors at a Grassland in Berkshire, England, May 28-June 28, 1981

20 40 60 80 100 120 1 4 8 1 5 1 5 2 1 5 4 1 5 6 1 5 8 1 6 1 6 2 1 6 4 1 6 6 1 6 8 1 7 1 7 2 1 7 4 1 7 6 1 7 8 Day N H $ + a n d N O 3

• (

k g N /h a ) 2 4 6 8 10 12 D O C ( k g C /h a ) , A N V F NH4+ NO3- DOC Eh

Two N2O peaks were caused by fertilization and rainfalls at a grassland in England (Field data from Ryden 1983)

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• 2

2 4 6 8 10 1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 Day N2O flux, g N/ha/day Field Model 1 2 3 4 5 1 19 37 55 73 91 109 127 145 163 181 199 217 235 253 271 289 307 325 343 361 Day Eh or Substrate (kg N or C/ha) NH4+ NO3- DOC ANVF

Low N2O fluxes were measured at a grassland in

• Colorado. Both nitrate and

DOC were limiting factors. (Field data from Mosier et al., 1996)

10 20 30 40 50 60 70 80 90 314 320 326 332 338 344 350 356 362 3 9 15 21 27 33 39 45 51 57 63 69 Day N2O flux, g N/ha/day Field KC3 Field KC4 Model 5 10 15 20 25 314 320 326 332 338 344 350 356 362 3 9 15 21 27 33 39 45 51 57 63 69 Day NH4+ NO3- DOC ANVF X 10

Two high peaks of N2O flux were caused by fertilization at a corn field in Costa Rica, 1994.

(Field data from Crill et al., 1999) N2O Fluxes from a Organic Soil at Glades, Florida, 1979-80

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 106 123 140 157 174 191 208 225 242 259 276 293 310 327 344 361 13 30 47 64 81 98 115 132 149 166 183 200 217 234 251 268 285 302 319 336 353

Day N2O flux, g N/ha/day

Field Model 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000

Observed N2O emission, kg N/ha/yr M o de le d N2O e mission, kg N/ha/yr Colorado, unfertilized Costa Rica, unfertilized Costa Rica, fertilized Beijing, unfertilized Beijing, fertilized Germany, fertilized Jiangsu, fertilized Florida, unfertilized

Comparison of Measured and Modeled N2O Fluxes from 8 Agricultural Sites In the U.S., China, Germany, and Costa Rica

N2O and NO from Forests: Comparisons between

• bserved and modeled fluxes

from 28 forest stands in Europe and the U.S.

(from dissertation of Florian Stange, Fraunhofer Institute for Atmospheric Environmental Studies, Garmisch- Patenkerchin, Germany, 2000)

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Application 1: Predicting mitigation options

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Application 2: Regional Inventory

U.S. agricultural land emitted 876 Tg CO2-C in 1990 U.S. agricultural land received 1153 Tg residue-C in 1990 U.S. Agricultural Land gained 460 Tg SOC in 1990

DNDC-Modeled C Storage in and Fluxes from Agricultural Land in the U.S. in 1990

C storage in cropland, 1990 C storage in grassland and pasture, 1990

Cropland Grassland and pasture Acreage (million ha) 141.2 204.5 C storage in 0-30 cm (Tg C) 7898.8 4155.7 Incorporated plant residue (Tg C) 331.7 821.4 Manure amendment (Tg C) 81.0 76.5 CO2 emission (Tg C) 446.8 428.7 CH4 emission (Tg C) 0.05

• 0.03

DOC leaching (Tg C) 7.9 2.4 SOC change (Tg C)

• 7.0

466.9

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http://www.dndc.sr.unh.edu